NEW YORK — Beneath all of the controversy surrounding the Terri Schiavo case is an important detail about what brought on her condition in the first place: complications from an eating disorder that caused heart failure and led to severe brain damage.

Schiavo's case is tragic for innumerable reasons, but it should also serve as a wake-up call that eating disorders can have serious, sometimes fatal consequences.

Robert Bazell, NBC News’ chief science correspondent, explains the dangers of eating disorders and why Schiavo's case should be a cautionary tale to many.

How is it that an eating disorder can lead to heart failure and, in the extreme case of Schiavo, a vegetative state?
Well, fortunately, it is very rare that this can happen. But when people have bulimia, which is what Terri Schiavo is reported to have had, people eat large amounts and then purge themselves by either vomiting or using laxatives extensively.

Bulimia can cause a sudden dehydration of the body that causes an imbalance in electrolytes, and particularly potassium. When that happens, it can cause irregularities in the electrical signal, so it can cause the heart to stop beating. That is reportedly what happened to Terri Schiavo.

No one really knows how prevalent eating disorders are in the [U.S.] population. There have been reports that it is from 1 percent of the entire population in the United States to up to 7 percent of young women in America. So, it is an extraordinarily common problem, which is not surprising given our obsession with body image and the problems with being overweight that we are challenged with all the time.

How common is it for eating disorders to lead to this sort of complication?
The two major kinds of eating disorders are anorexia, where people basically just starve themselves, and bulimia, which is what Terri Schiavo is reported to have had.

There are more reports of people hurting themselves with anorexia because clearly, they are just simply starving and they can get into a lot of medical trouble.

However, there are plenty of reports of people who do have bulimia, like Terri Schiavo, [suffering serious consequences]. [The rate of complications] is not one in 100 or anything like that — it’s fairly rare. But because the consequences can be fatal, it is certainly something that needs to considered when someone is questioning whether or not an eating disorder is something to be worried about it. It is.

What are some of the other long-term effects of eating disorders?
We need to remember that men suffer from eating disorders, too. But clearly it is more common in women.

The biggest thing with bulimia is that because people vomit, it rots their teeth. But the other major problem is that there are all kinds of psychological consequences. It has to do with people having a bad self-image and a lot of psychologists and psychiatrists believe that if you don’t treat the underlying problems that are causing it, then you don’t cure the disease.

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Also people who vomit constantly can have damage to their esophagus, as well as their teeth.

What about the effects on women’s fertility?
Well, it's interesting that you bring that up. Terri Schiavo’s husband, Michael, said in a 2003 interview with CNN’s Larry King that he and Terri were trying to have a baby. But they were not achieving their goal.

It is very common for women with eating disorders not to menstruate. In fact, the reason why Terri Schiavo won a judgment against a fertility specialist was that Michael Schiavo alleged that the fertility specialist should have been able to notice that she was having an eating disorder and diagnose it before it became potentially damaging to her brain.

Fertility is definitely an issue with eating disorders. In fact, it’s more of an issue with anorexia because women that are so thin that their bodies are starving don’t menstruate. That is well known from famines and things like that.

Even though the Schiavo situation is an extreme case, how can it serve as a message about eating disorders?
It can serve as a message that this behavior that is often undertaken by women to control their body weight can often have horrific consequences. In this case, it was severe brain damage. She will probably end up dying basically because of an eating disorder. If it wasn’t for that, all of the rest of this wouldn’t have happened.

Her heart stopped beating and the paramedics got there, but by the time they revived her, it had been too long. Her brain had been deprived of oxygen for so long that it actually ended up being severely damaged.

It’s interesting in terms of the medical aspects of the Schiavo case. One of the things that a lot of neurologists will point out is that people are more likely to recover from an injury to the brain — like an automobile accident or a fall or something like that — than this kind of situation when oxygen is deprived to the brain for a long time, because that destroys the entire brain throughout. It is not just an injury to one part.

How are eating disorders treated?
It is a complicated business because there is a lot of shame and it is really difficult to treat eating disorders.

It is not as though you can say to someone, “Hey, knock it off.” People who are anorexic and are literally starving themselves to death will look at themselves in the mirror and think they are fat still. People who are bulimic are vomiting regularly. They will go and eat a large meal and then go off and vomit. It is quite humiliating.

It is a mental problem and, therefore, it can be very difficult to get over. It is not just caused by body image issues — there are a lot of other problems at hand.

So, there is no simple answer. There are Web sites and there is a lot of advice out there and a lot of people are treated for this. But it turns out that it is a difficult thing to treat the underlying psychological problems.

But, one of the things about the Schiavo case is that this is a wake-up call that this sort of thing can have very serious consequences.